the birds and the bees and...general contractors

During pick up yesterday my girl musketeer who is all of 5 years old asked the grumpy prince 'the' question, the where did we come from question...

it went like this:
she asked: "papa, what did you use to make us?"
gp: "...what do you mean make us?"
she asked: "how did you build us?" "you know, build me and the boys?"
gp: "build?..." "oh...well...we made you"
she asked: "what materials did you use?"
gp: "ask your mother, she used most of the materials"